Validation of UHPLC-MS/MS Method and Measurement Uncertainty Evaluation for Lactose Quantification in Lactose-Free and Regular UHT Milk

Freeze-dried human milk microcapsules using gum arabic and maltodextrin: An approach to improving solubility

Human milk (HM) is essential for newborns' food, but its low storage stability is a limiting factor so that microencapsulation may stabilize and protect compounds sensitive to degradation. This study investigated the action of maltodextrin and gum arabic on freeze-dried HM concerning its quality and solubility. Microencapsulation was evidenced by morphology, and all samples presented high encapsulation efficiency (>85 %), proving to be an efficient process. Furthermore, specific signals in the Fourier-Transform Infrared (FTIR) spectra indicate the interactions between the coating materials and the HM matrix. Gum arabic improved the reconstitution properties of freeze-dried HM (higher solubility, 3 % on average, and lower dissolution time, around 80 %), elucidating its high stabilization capacity, even at low concentrations (5 and 10 %). Despite the best results reached by gum arabic, the addition of maltodextrin proved effective; in other words, its low stabilization capacity enables combinations with gum arabic. A lower polidispersibility (difference of 20 % between samples: control and containing gum arabic) was also observed, which means that the encapsulated samples were more homogeneous. Therefore, through the analysis performed, we recommend using gum arabic alone or with maltodextrin to obtain HM microcapsules with a good quality of reconstitution.

UHT Milk Characterization by Electrical Impedance Spectroscopy

Ultra-High Temperature (UHT) pasteurized milk is the most diffused variety of milk in Europe. In this paper, a method is presented, employing Electrical Impedance Spectroscopy to characterize the different commercial milks commonly available in grocery stores and supermarkets. The curves of the measured admittance allow for the classification of the type of milk (whole, semi-skimmed, fat-free) and to distinguish lactose-free milk. An electrical circuit model has been derived and different values of circuit parameters add interesting information on the classification of the samples. Furthermore, the characterization allows for the identification of the degradation of the milk before it is visible to the eye, thus highlighting the difference between storage in the fridge and at room temperature, and identifying expired milk.